Re: BUG #13643: Should a process dying bring postgresql down, or not?

Amir Rohan wrote:
> On 09/27/2015 09:59 PM, Alvaro Herrera wrote:
> > amir.rohan@mail.com wrote:
> >
> >> postgres     2181  0.0  0.1 134468  9504 pts/0    T    03:34   0:00 /usr/local/pgsql/bin/postgres -D
/home/local/pg/s1
> >> postgres     2183  0.0  0.0 134576  4168 ?        Ss   03:34   0:00 postgres: checkpointer process
> >> postgres     2184  0.0  0.0 134604  2844 ?        Ss   03:34   0:00 postgres: writer process
> >> postgres     2185  0.0  0.0 134468  2780 ?        Ss   03:34   0:00 postgres: wal writer process
> >> postgres     2186  0.0  0.0      0     0 ?        Zs   03:34   0:00 [postgres] <defunct>         <<<<<<<<<<<<<<<
deadprocess 
> >> postgres     2187  0.0  0.0 127300  2204 ?        Ss   03:34   0:00 postgres: stats collector process
> >> postgres     2193  0.0  0.0 118164  2696 pts/0    T    03:34   0:00 pg_basebackup -D /home/local/pg/backup -p
57833--format=t -x 
> >> postgres     2194  0.0  0.0 134916  6016 ?        Ss   03:34   0:00 postgres: wal sender process user1 [local]
sendingbackup "pg_basebackup base backup" 
> >
> > That postmaster is in STOPped mode is the issue here.  That doesn't
> > happen unless you take specific action to do that.
>
> I hadn't noticed that.  That looks like I suspended pg_ctl during start,
>  but with the backup in progress already, it's not clear how I managed
> that state. There was no kill -SIGSTOP involved...

Suspending a process *is* sending sigstop.  You may not have sent
sigstop explicitely, but the shell would have done it if you suspended
the process.

Since pg_ctl is not normally long-lived, I'm not sure how you ended up
suspending it.

> After killing some subprocesses in random I do see postgres
> restarting the whole group once one goes down, if/once its
> running/unsuspended.

Well, doing things randomly is unlikely to teach you much ...

--
Álvaro Herrera                http://www.2ndQuadrant.com/
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